Breed Structure of Pedigreed Hereford Cattle in Canada

A study of the Canadian pedigreed Hereford cattle population was carried out to determine breed structure and to determine if interherd selection decisions were related to measures of performance. The group of calves born in 1982 (N = 53 352) was the reference population for this study. There was a clear subdivision of the pedigreed population according to the horned-polled status of individuals. 52.54% of calves were phenotypically polled calves with both parents polled, 41.82% of calves were horned calves with both parents horned; the remaining calves were the result of mating parents of different horned-polled phenotype or were different in phenotype from their parents. There appeared to be a very high level of interherd transferrals of parents: in herds registering fewer than 10 calves only 5.38% of sires and 31.68% of dams were homebred. In herds registering larger numbers of calves more parents were home-bred. A hierarchy among herds was found to exist in each of the horned and polled subpopulations with three strata in the horned group, two strata in the polled group, and a relatively small effective number of primary (or "nucleus") breeders' herds in both cases. The association between popularity of a herd (denoted as the number of herds to which sires were transferred) and herd average sire proofs for calving ease, preweaning gain and gain from birth to yearling age was evaluated using multiple regression (R2 = 3.45). Only average calving ease proof of a herd had any significant (P < 0.05) association with herd popularity. Higher average calving ease proof for a herd was associated with higher popularity of a herd, but only up to a point since the regression was quadratic.